Product labels, on which the contents of products, compositions of products, place of production, production number, production date, and barcode are printed are applied to industrial products and packages therefor. Since the above information varies depending on each product, mass production of one label cannot be performed. Due to this, printing is performed on a label, which has a breakable print recording layer facilitating production in small lots, by a thermal printer, laser, an electric discharge printer, or the like. However, recently, counterfeit products having falsified product labels applied thereon or counterfeit products having genuine product labels peeled from genuine products are on market, and a large amount of damage is caused. In order to prevent the above illegal use of product labels, techniques for discriminating the authenticity of product labels are needed.
Patent Publication 1 discloses a technique in which plural colored layers are used, although the number of colored layer is generally one, and depth of breakage caused by a thermal head is controlled in order to show plural mixed colors and color tone, and the colored layer is combined with the color tone of a printed layer in order to form a complicated pattern. Patent Publication 2 discloses a technique in which a thermal breakage type print recording layer and an electric discharge breakage type print recording layer are provided, and breakable print using characteristics of the layers is simultaneously formed on a surface and a reverse surface. Patent Publication 3 discloses a technique in which a thermal breakage type print recording layer and a hologram are combined and designability and difficulty of counterfeit holograms are provided to a thermosensitive recording paper.
The Patent Publication 1 is Japanese Unexamined Patent Application Publication No. Hei 6-15985. The Patent Publication 2 is Japanese Unexamined Patent Application Publication No. Hei 6-106882. The Patent Publication 3 is Japanese Unexamined Patent Application Publication No. Hei 8-80680.